There is a really nice and simple-to-use module called Tie::File, which allows you to access a file as if it were a perl array :

use strict;
use Tie::File;
my @file;
my $filename = 'test.txt';
tie @file, 'Tie::File', $filename
  or die "Couldn't open '$filename' : $!\n";

die "The second line in '$filename' is not blank !\n"
  unless $file[1] eq '';

# Remove first line :
shift @file;

# Remove second line :
shift @file;

# Replace first (former third) line :
$file[0] = "New text";
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perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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